1. Technical Field
The present invention relates to a vibrator, an oscillator provided with the vibrator, an electronic device, and a moving object.
2. Related Art
An electro-mechanical system structure (for example, a vibrator, a filter, a sensor, or a motor) provided with a mechanically movable structure which is called a micro electro mechanical system (MEMS) device which is formed by using semiconductor micro fabrication technology, is generally known. Among these, compared to an oscillator and a resonator using quartz crystal or a dielectric in the related art, since a MEMS vibrator is easy to be manufactured by incorporating a semiconductor circuit and advantageous in miniaturization and high functionality, the usage range thereof widens.
As representative examples of the MEMS vibrator in the related art, for example, a comb type vibrator which vibrates in a direction parallel to a substrate surface provided with the vibrator, and, for example, a beam type vibrator which vibrates in a thickness direction of the substrate, are known. The beam type vibrator is a vibrator which has a fixed electrode formed on the substrate or the movable electrode separated and disposed on the substrate, and according to a method of supporting a movable electrode, a cantilevered beam type (clamped-free beam), a double-end supported beam type (clamped-clamped beam), or a both-ends free beam type (free-free beam) are known.
In the MEMS vibrator in a cantilevered beam type in JP-A-2012-85085, in a side surface portion of a first electrode provided on a main surface of the substrate, a corner of the side surface portion provided on a supporting portion side of a movable second electrode is formed substantially perpendicularly. For this reason, it is possible to reduce an effect of the variation of a vibration characteristic caused by a variation in an electrode shape, and to obtain a stable vibration characteristic.
However, the MEMS vibrator in JP-A-2012-85085 is advantageous in that the size thereof can be reduced since there is one supporting portion. However, since the mass of the supporting portion which fixes the cantilevered beam is small, there is a problem in that a Q value deteriorates due to a energy dissipation in which flexural vibration of the beam is transmitted through the supporting portion and is transferred to the entire substrate, and in that a high Q value cannot be obtained and a stable vibration characteristic or a desired vibration characteristic cannot be obtained according to the deterioration of the Q value due to a thermoelastic damping generated by the supporting portion where the stress of flexural vibration is concentrated.